I was beaten by penguins

Bruce Millar finds it takes him five minutes to overtake a baby

The starter's gun echoed across Blackheath Park at 9.30am precisely - and we're ... we're still standing stock still 40 abreast and several hundred deep, squashed so tight that the last few runners are ripping their bin-liners off Superman style - there's not enough elbow room to take them off properly. Ahead, the lite runners are already opening up a big lead.

Two minutes later, a cheer goes up as we inch forward, hit walking pace and eventually break into a trot. We finally begin to run, and cross the starting line with 6min 14sec already on the clock.

I felt tired after a mile or so, which came as no surprise from my training, but soon settled into a rhythm, cruising along with minimal effort, notching up the sub nine-minute mile needed to reach my four-hour target.

It felt good: a touch on the accelerator here, a slight break there. I fantasised about the Big Finish. Almost half-way, and I crossed Tower Bridge feeling slightly despondent because my family was nowhere to be seen (I later discovered they were in a multi-storey car park cheering me on). Still, I was feeling in control as we headed back east into the Docklands.

I crossed the half-way mark on schedule, then, suddenly, it all went wrong. The news came through that Dionicio Ceron had won in 2hr 11min, so the race was over. I had lost. My mile-times got slower. I realised how slowly I was running - OK, shuffling - when it took five minutes to overtake a young couple out for a Sunday-afternoon stroll with their baby in a pram.

The pain was beginning to take control as we hobbled over the cobbles past the Tower of London. First I was overtaken by a man wearing a chicken suit; then by Fred Flintstone and Barney Rubble in matching leopardskin and brandishing clubs; then by a penguin with a big orange beak, and a red devil complete with tail.

Then a strange thing happened; with two miles to go I found myself accelerating. I was striding out, my legs no longer hurt - perhaps they were numb with fatigue. By now, most were walking or shuffling, and I was running past them. At the 80-metre marker I pressed on the accelerator again and, amazingly, there was more to give. I crossed the line, arms aloft, a few seconds behind the penguins.

Four hours and 33 minutes was the official time - that's 4:27 in my book. Will I do it again? I'm not sure; but Lausanne in October is looking attractive.